PB2373: A SINGLE-CELL ATLAS OF HIV-ASSOCIATED DIFFUSE LARGE B-CELL LYMPHOMA
Authors: Xiaomei Zhang, Zailin Yang, Huihui Fu, Sanxiu He, LI Jun, Yi Liu, Yao Liu
Journal: HemaSphere (2023)

Topic: 20. Lymphoma Biology & Translational Research Background: Human immunodeficiency virus (HIV) infection is associated with an increased incidence of malignancy. Diffuse large B cell lymphoma (DLBCL) is the most common cancer in HIV-positive patients, even after the introduction of combined antiretroviral therapy. Recently, the single-cell atlas of lymphoma is gradually revealed by Single-cell RNA-Sequencing (scRNA-Seq). Aims: The tumor cell population diversity and immune microenvironment of HIV-associated DLBCL are still unknown. The precise characterization of HIV-associated DLBCL may be conducive to more effective molecular targeted therapies and more immunotherapy strategies. Methods: scRNA-Seq was performed on tumor samples from 5 newly diagnosed DLBCL patients, three of whom were HIV-infected. Additional controls include 1 PBMC from a healthy person and 1 reactive hyperplastic lymph nodes. We used SeekOne-Digital Droplet platform (Seekgene) to prepare individually barcoded scRNA-Seq libraries. Sequencing was performed using Illumina high-throughput sequencing platform. Seurat version 4.2.0 was used to process the raw matrix. The cells expressing fewer genes (<500) or exhibiting higher rates of mitochondrial transcripts (>20%) were removed. The sequencing data were normalized and Scaled with SCTransform. Dimension reduction was performed using principal component analysis. The top 30 principal components were further summarized using UMAP. Results: Qualified data from 14,286 single cells were obtained from 5 DLBCL samples, with an average of 2,857 (966–5,742) cells for each sample. There were 7198 single cells from HIV associated DLBCL and 7088 single cells from non-HIV associated DLBCL. Both groups contained the same cell types, including B cells, CD8 T cells, CD4 T cells, macrophages, fibroblasts, endothelial cells, plasmacytoid dendritic cells, mast cells and plasma cells. In addition, B cells (54.21%) were the major cell types, and T cells (27.12%) were the most dominant cell type within tumor microenvironment cells followed by myeloid cells (13.35%) both in HIV associated and non-HIV associated samples. The radio of CD4/CD8 T cells in DLBCL samples from HIV infected patients was lower than that from HIV uninfected patients (0.18 vs 0.99). These B cells from DLBCL samples and control samples could be grouped into 8 distinct clusters. The B cells from HIV associated DLBCL were contained mainly in clusters #1, 3, 4, 6, 8 (HIV associated clusters), whereas the B cells from non-HIV associated DLBCL were enriched in clusters # 0, 2, 7 (non-HIV associated clusters). The B cells from control samples were dominantly grouped into cluster #5. The genes increased expression in HIV associated clusters enriched in ATP metabolic process, oxidative phosphorylation, regulation of chromosome organization, ribosome biogenesis, DNA replication and nuclear division, whereas the marker genes in non-HIV associated clusters enriched in leukocyte cell-cell adhesion and regulation of T cell activation. We also observed the increased expression of genes associated with malignant proliferation (MKI67, LDHA, HMGB2) in HIV associated clusters. Summary/Conclusion: There was similar cell composition in HIV-associated and non-HIV-associated DLBCL samples. However, HIV-associated DLBCL samples had a low CD4/CD8 ratio due to HIV infection. Noticeably, the malignant B cells in HIV-associated DLBCL are distinguished from those in non-HIV-associated DLBCL, especially the malignant B cells in HIV-associated DLBCL have stronger metabolism activity and malignant proliferation ability, which augurs well for the rapid progression of HIV-associated DLBCL. Keywords: B cell lymphoma